This invention relates generally to a combined microfilm viewer and film copier, and more particularly to such a viewer as having an attachment for the production of enlarged copies of the microfilm.
A typical microfilm viewer includes a light means, a microfilm holding device, a projecting lens, means for deflecting the beam of light issuing from the projecting lens and a projection screen for viewing the transillumination, such elements being arranged in a single cabinet in such a manner that the film holding device may be operated and the projection screen viewed from an unchanged position of the operator. The optical axis common to the light means and to the projection lens is set at an angle of between 10.degree. and 30.degree. above a horizontal plane, and a single surface mirror is disposed at the back wall of the cabinet for deflecting the light beam onto the projection screen.
Known microfilm viewers of the type described and of other designs are constructed in such a manner as to facilitate proper viewing of the microfilm records, but are not capable of producing an enlarged copy thereof onto light-sensitive copy material. On the other hand, there are also microfilm viewing and enlarging machines with which it is possible to alternately view microfilm records and/or to produce copies of enlargements thereof. The known devices of this latter type differ from the viewers discussed above both in their mechanical construction and in their optical system. There are believed to be no known microfilm viewers that are capable of being effectively converted into a combined microfilm viewer and copy enlarging machine simply by the addition of a few elements, either at the place of manufacture or by the user of the viewer. Thus, if one having a microfilm viewer should ever need to make copies of the enlargements of the microfilm records, it would need to be done with the use of some other machine perhaps outside the user's office location, which is not only troublesome but time-consuming, or a completely separate microfilm viewer and enlarging copy device would need to be obtained, which is costly and requires additional space for the copy machine. Because of the different mechanical construction of the microfilm viewer on the one hand and the microfilm viewer and enlarging copy device on the other, completely different cabinets and other parts must be developed and produced for the two machines, which of course increases the cost of manufacture and the storage space.